Printing mechanisms



July 7, 1959 Filed Aug. 20, 1957 T. o. WRlGHT ET AL 2,893,311

PRINTING MECHANISMS 2 Sheets-Sheet l INVENT s 7! H06 awn/93m,- JQI/OR l nmwv R166) ATTORNEYS United States Patent PRINTING MECHANISMS Thomas Oliver Wright and Ivor Vivian Rigby, Letchworth, England, assignors to International Computers and Tabulators Limited, a British company, London, England Application August 20, 1957, Serial No. 679,236

Claims priority, application Great Britain September 7, 1956 8 Claims. (Cl. 101-93) This invention relates to printing mechanisms in which type selection is effected under control of timed impulses, such as may be obtained from the sensing of punched record cards, for example.

It is the object of the invention to provide a printing mechanism, employing a type wheel or wheels, in which at least two printing operations may be performed during each revolution of a type Wheel. This increases the printing speed with the type selecting and drive mechanisms operating at a given speed, as compared with a printing mechanism in which only a single printing operation takes place for each revolution of the type wheel. The printing speed of a particular mechanism is often limited by the speed at which the type selecting mechanism can be operated satisfactorily, so that the invention facilitates the provision of a mechanism having a relatively high printing speed.

According to the invention a cyclically operable printing mechanism includes a typewheel with a plurality of sequentially arranged groups of type characters and selecting means operable in each cycle to position any one of the characters of only one of the groups for printing under the control of a corresponding timed character representing pulse or pulses, the selecting means being effective for different ones of the groups in successi-ve printing cycles.

According to another aspect of the invention the typewheel may have at least two groups of type characters arranged sequentially round the periphery of the wheel, the selecting means being operable in response to timed character-representing pulses for selecting type characters for printing during a succession of printing cycles, one type character being selected in each cycle, means being provided for moving the typewheel to one of a plurality of reset positions after printing has taken place, one reset position being associated with each of the groups of characters, the said movement being effective to position the typewheel in the reset position associated with the next or another group from which the selection of a character is to be made in the next following printing cycle.

According to a further aspect of the invention the printing mechanism may have a plurality of typewheels, each typewheel carrying a plurality of groups of type characters arranged sequentially around the periphery of the wheel, means for generating timed character-representing impulses during a succession of printing cycles, selecting means individual to each typewheel and operable in response to said impulses in eachcycle to position the wheel to print a selected character, means operable after printing has taken place tocause each wheel to be moved to a reset position associated with the next group of characters from which selection of a character is to be made during the next printing cycle of that wheel, one such reset position being provided, for each group, and means for terminating the movement of each typewheel on reaching the said reset position.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a sectional elevation of the printing mechanism;

Figure 2 is a timing chart;

' Figure 3 is a circuit diagram, and Figure 4 shows a typewheel.

The printing mechanism consists of a plurality of typewheels 27, each bearing four groups of numerical type representing the characters 0 to 9, as shown in Figure 4. Each wheel is controlled by a chain of gear wheels from a mechanical clutch, which is engaged by means of an electro magnet operable by an electrical impulse timed in relation to the operating cycle of the machine and is disengaged by a cam-operated mechanism.

The type wheels are closely spaced to produce a single line of printed information at each operation, and in order to increase the space in which their operating mechanisms may be accommmodated certain of these latter are arranged in staggered formation. The displacement of such mechanisms is indicated in Figure l, where corresponding elements of adjacent Wheels are referenced with similar numerals, the references for one group of elements being sufiixed a.

Timed electrical impulses for the operation of the typewheel clutches may be derived from record cards containing columns in which holes representing the digits 0 to 9 may be punched. Such cards may be sensed 'by any suitable mechanism, such as, for example, that shown in British Patent 605,132.

Figure 1 shows in detail the arrangement of the controlling mechanism for one type wheel. An impulse resulting from the sensing of a hole in a column of a record card is applied to a start electro magnet 1 which is mounted in a yoke 2 secured to one of a number of plates (not shown) provided at suitable intervals across the width of the printing mechanism.

The magnet 1 is provided with an armature 3, pivoted at a point 122, so that when the magnet 1 is energised the armature 3 will move in a clockwise direction. The armature engages with a slot 4 in an arm 5. Energisation of the electromagnet will turn the arm 5 counter-clockwise about a pivot 6, so that a V-shaped end 7 of the arm 5 will be moved from a notch 8 into a notch 9 of a detent member 10. The detent member 10 is supported in a slot 11 in a comb-bar 12 and is pivoted about a point 13. The action of a spring 14 on a plunger 121 maintains the detent member 10 in engagement with the end 7 of the arm 5. A projection 15 on the arm 5 will be moved out of engagement with a tooth 16 on a plate 17 when the magnet is energised.

The plate 17 forms part of a clutch which may be engaged at any one of a number of points in each revolution and is associated with a plate 18 and a gear 19 in such a manner that the withdrawal from engagement of the projection 15 allows the coupling of the plates 17 and 18 and the gear 19 with a notched shaft 20 by means of a pawl mechanism (not shown). The construction of a similar clutch mechanism is described in detail in British patent specification No. 704,764.

The shaft 28 is continuously driven in a counterclockwise direction by the main drive motor (not shown) of the machine, which also drives the card sensing mechanism, so that it performs one revolution during each operating cycle of the machine. mitted through the clutch mechanism to the gear 19 meshing with a gear 21, which is fixed to another gear 23 and a cam plate 22, all of which are freely mounted on a shaft 24. The gear 23 meshes with another gear 25 mounted freely'on shaft 26. The gear 25, is in turn,

Motion of the shaft 2%) is transmeshed with the type-wheel 27, which is freely mounted on a stud 28 on a plate 29. The ratio of the gears is such that the typewheel will complete half a revolution for one revolution of the shaft 20 if the clutch mechanism is engaged by the energisation of the start magnet 1.

Disengagement of the clutch is achieved by the operation of an arm 30 which is pivoted about the point 6, and restrained from lateral movement by the projection of its end 31 into a comb-member 32. -An upturned lug 33 of the arm 36 bears against the arm 5, so that if the arm 30 is turned in a clockwise direction, it will carry the arm with it and the projection 15 on the arm 5 will be interposed in the path of the teeth 16 of the plate 17. During the period of disengagement of the clutch, the typewheel is held stationary by the co-operation of an arm 35, with notches 34 in the plate 18. The arm 35 is pivoted at 36 and is urged into engagement with the notches 34 by the action of a plunger 37 and a spring 38. These latter are supported in a comb bar 39, which also supports the arms 35.

During one operating cycle two disengagements of the clutch are required. The first occurs when the selected type has been brought to the printing position and the second occurs towards the end of the cycle, when the type wheel has arrived at its normal or reset position. The first disengagement is arranged to take place always at a fixed point in the cycle, and is controlled by a shaft 40, which makes one revolution during each operating cycle, being driven by'any suitable means from the main drive of the machine. A projection 41 on the shaft 46 cooperates with a camming face 42 of the arm 31 to move the arm 30 in a clockwise direction.

A. corresponding movement of the arm 39 during the resetting movement of the typewheel is obtained by the action of an arm 43 co-operating with the cam plate 22. In its normal or reset position the typewheel is brought to rest with a 0 type at the printing position. Since there are four blocks of type set round the periphery of the typewheel 27, there are four possible reset positions. When the typewheel is in a reset position, end 95 of the arm 43 rests in one of four notches 44 in the cam plate 22.

The cam plate 22 rotates in a clockwise direction when the typewheel is being driven. Immediately before the typewheel reaches a reset position, the end 95 of the arm 43 will ride up a projection 45 of the cam plate 22. The end of the arm 43 is held in contact with the periphery of the plate 22 by a plunger 97 and a spring 98, and is supported by a comb bar 96. The engagement of the projection 45 with the end 95 of the arm 43 causes the arm 43 to turn in a counter-clockwise direction, and a projection 47 on its lower edge strikes a lug 48 of a bellcrank lever 49, which is housed in the comb-bar 32 and pivoted at a point 50. The end 51 of the bell-crank lever strikes the end 31 of the arm 36 and causes the arm to move in a clockwise direction, thus disengaging the clutch, so that the typewheel comes to rest in the correct reset position.

Selection of a type takes place during the first half of the operating cycle and resetting of the typewheel takes place during the second half cycle, the total movement of the clutch for both these operations being half of a revolution. Since the ratio of the gears is such that the gear 19 makes two revolutions for each revolution of the typewheel 27 it will be apparent that during type selection and resetting, the typewheel 27, will move only one quarter of a revolution.

During an operating cycle one of the digits 9 to 1 (Figure 2) will be sensed, and an impulse to the start magnet will occur at one of the index points shown between 9 and 153 in the cycle, depending on the value of the digit sensed. By way of example, it will be assumed that the digit 4 has been sensed. At 99 in the cycle the start magnet will be energised and will cause the clutch to be engaged to move the-typewheeL The spacing of the type on the typewheel is such that one type will pass the sented by four index points, and the type 4 will be at the printing position.

After printing has taken place, in a manner to be described, a reset start impulse will be transmitted to the start magnet, at 192 in the cycle, and the clutch will again be engaged. As the typewheel again approaches the next reset position, the arm 43 (Figure 1) will be moved by one of the projections 45 to cause operation of the arm to disengage the clutch. The entire sequence of events will be repeated in the following operating cycle.

Printing is controlled by a cam shaft 52, which has a notch 53 co-operating with a nose 54 of the plate 29 to which the type wheel shaft 28 is secured. The plate 29 is pivoted on the shaft 26 and is biased to rock in a clockwise direction by a compression spring 55, in a hole 58 in a comb-bar 56, acting on a tail 57 of the plate 29. The action of the nose 54 on the surface of the cam shaft 52, holds the plate until, at 174 (Figure 2) in the cycle, the nose 54 (Figure 1) enters the notch 53 and the tail 57 moves downwards as the plate 29 rocks clockwise. The tail 57 is urged downwards by the spring ,paper 60, which is fed over rollers 61, and supported by a platen 62 of nylon held in a block 63. The force exerted by the spring-55 on the plate 29 may be adjusted by means of a screw 64. Adjustment of the force of the printing impression is achieved by the movement 10f a plate 65 upon which the comb-bar 56 is mounted.

the pivots 66 by the action of eccentric studs 69 operating in slots 70 in the plates 65, and will thus move the combbar 56 upwards or downwards so that the typewheel plates 29 are released at their tails 57 from the springs 55 at an earlier or later point.

Since the typewheel 27 comes to rest after a resetting operation with an 0" type at the printing position it is not moved by the operation of the start magnet 1 when a '0 is to be printed. In many cases it is desirable to suppress the printing of 0s to the left of the first significant digit in a line of digits, and the printing of a 0 is controlled by an electrical circuit, to be described, in conjunction with a typewheel locking lever 71. This lever is pivoted on a shaft 72 and biased by a spring 73 which is secured to a bar 74. Nose 75 of the lever 71 is held in one of four notches 76 in the periphery of a plate 77, secured to the gear 25, when the typewheel is in its reset position. An upturned lug 78 of the locking lever 71 lies in an aperture 79 in the typewheel mounting plate 29 and prevents the plate from rocking in a clockwise direction. When a type other than 0 is selected, the plate 77 rotates with the gear 25 and the nose 75 of the locking lever is lifted out of the notch 76, so that the lug 78 moves upwards in the apertom 79 and clears the shoulder 80. This allows the plate 29 to be rocked to effect printing.

In order to allow printing of the numeral 0," an electro-magnet 81 is energised. and attracts its armature 82, to which is attached a pull-wire 83 secured at its other end to a bell-crank lever 84 also pivoted on the shaft 72. One end 85 of the bell-crank lever 84 co-operates with the lug 78 of-the locking lever 71 and is maintained in contact therewith by the action of a spring 86. En-

ergization of the magnet 81 causes the bell-crank lever to turn in a counter clockwise direction and raise the lug 78 clear of the shoulder 80, thus allowing the plate 29 to rock under control of the cam 53.

The second arm of the bell-crank lever 84 co-operates with a projection 87 of a latch arm 88, which is pivoted at a point 89 and supported in a comb-bar 90. When the bell crank lever is moved by the operation of the magnet 81, the arm 88 is urged downward by a spring 91, so that the projection 87 enters a notch 92 in the bell crank lever 84 to maintain it in its operated position. A pin 94 in the typewheel plate 29 engages end 93 of the arm 88 and lifts the projection 87 out of the notch 92 as the plate 29 rocks clockwise during the printing operation to allow the bell-crank lever 84 to restore to its normal position.

The electrical circuit for the operation of the magnets 1 and 81 for the selection of type to be printed is dependent on the operation of interlock contacts, asso ciated with the arm 43, which is moved in a counter clockwise direction whenever the plate 22 is moved from its reset position due to the engagement of the clutch mechanism. One end of the arm 43 carries a pin 99 which engages with a slot 100 in a slider 101 which is carried in two-comb-bars 102 and retained by caps 103. The slider carries a block 104 of insulating material which engages contact springs 105, which co-operate with contacts 106 and 107 mounted in av block 108 of insulating material carried by bars 109.

I The circuit diagram (Figure 3) shows the electrical arrangements for controlling the operation of the printing mechanism. The mechanism (not shown) for sensing the positions of holes punched in the record cards is connected between a supply line 110 and a plugboard connector 112, and the path for electrical impulses representing the values l to 9 is extended through a diode 113 and the magnet 1 (Figures 1 and 3) to a cam-operated contact 114 and thence to a supply line 111. T he contacts 114 are operated by a cam (not shown) which is driven in synchronism with the card sensing mechanism. The contacts are closed'throughout the sensing of the index points 9 to 1 (Figure 2) of the operating cycle, so that the magnet 1 will be energised for any of these impulses. Other columns of the card are sensed and the resulting impulses are passed to identical circuits of other typewheels which are shown in Figure 3 and whose reference, numbers are marked by a sufiix a or n. It is assumed that the sufiix n represents the column associated with the least significant of a group of digits and that within this group it is desired to suppress the printing of 0s to the left of the first significant digit. The printing of 0s by the energisation of the magnets 81 (Figures 1 and 3) is dependent on the operation of the contacts 106 and the provision of a path in the circuit to cam-operated contacts 117 (Figures 2 and 3), which are closed, during the time of sensing a hole in the 0 position of a card column. It will be assumed that the circuit suffixed a is associated with the selection of a significant digit, the circuits not sufiixed and suflixed n are associated with card columns in which a 0 hole issensed. The circuit from the plugboard connector 112n is extended over an alternative path to the magnet 81n and then to a plugboard connector 11622, which is connected, as shown by a dotted line, to plugboard connector 1154 associated with the contacts 106a, which have been operated, and thence to the contacts 117 and to the line 111, so that the magnet 8111 will be operated to cause a 0 to be printed. The equivalent 6 containing the contacts 107 so that only those wheels which have been selected are impulsed to cause a resetting operation.

Cam-operated contacts 119 (Figures 2 and 3) are made at 192 in the operating cycle and connect the line to the contacts 107 of all typewheels, so that for all wheels which have been selected the path is continued through the contacts 107, diodes 118, the magnets 1, cam-operated contacts 120, which close at the same time as the contacts 119, to the line 111, thus impulsing the magnets 1 and engaging the clutch mechanisms.

It will be appreciated that the number of printing operations per minute is the same as the number of revolutions per minute of the shaft 20. However, the mean speeds of the gear 19 and the gears 21, 25 etc. are only a half and a quarter of the speed of the shaft 20, respectively. Hence, the operation of the selecting and resetting mechanism, is less critical than in a mechanism in which the typewheel revolves at the same speed as the shaft 20. Furthermore, the shaft 20 runs at constant speed, as opposed to the arrangement described in British patent specification No. 704,764, in which the main driving shaft is accelerated during resetting.

In the embodiment described above, the shaft 20 has twenty teeth, corresponding to the twenty divisions of an operating cycle (Figure 2). If it is desired to divide the cycle in a different manner, the number of teeth on the shaft 20 are altered correspondingly. The shaft could rotate at half a revolution per operating cycle, for example, by providing twice the number of teeth.

It will be understood that more, or less, than four groups of type may be provided on the typewheel, the reduction ratio between the shaft 20 and the typewheel being chosen accordingly.

The number of type in the groups may also be altered, and the characters printed by the diiferent groups need not be the same. For example, some of the groups may contain alphabetical or numeral characters and others may contain symbols to be used in designating printed data, e.g. an asterisk and the :2 or .5 sign. Alternatively the groups may contain the same characters in different type founts. An example of the use of such groups occurs in the compiling of mathematical and other tables, where it is desirable to differentiate between succeeding lines of information. One Way of achieving this end is to print alternative lines in italics, or to print, say, every fifth line in heavy type. This difference is readily obtainable by the use of typewheels having groups of characters in the required founts.

However, when these typewheels are used in conjunction with the arrangements described for suppressing the printing of 0s to the left of significant digit means must be provided for maintaining all the wheels in synchronism, so that a wheel which has not been selected during one or more cycles is reset to the correct position to print from a particular group when a particular fount or symbol is required.

The resetting mechanism shown in Figure 1 may be modified to cause resetting to a particular position or positions in the following manner. The notch 44 in the cam plate 22 associated with the particular group or groups is made deeper, and an additional set of contacts, similar to those referenced 106, is provided in association with the arm 43. These contacts are arranged so that one pair of contacts are made when the arm 43 encounters the deep notch 44, and thus provide a means for identifying the particular reset positions. Since these reset positions occur at the beginning of predetermined groups of characters, selection is made from one of these groups during the following printing cycle.

The remaining pair of the additional contactsare madeat all times unless the arm 43 is in engagement with the deep notch, and these contacts are used to provide a circuit for the re-engagement of the clutch magnet during successive cycles until a predetermined reset position has been reached. At the same time the contacts also provide' means for suppressing printing until all Wheels are in synchronism. This suppression may conveniently be arranged by the provision of a clutch in the drive to the cam shaft 52.

An alternative way of ensuring that all typewheels remain in synchronism consists of applying a resetting movement to all the wheels whether or not they have been selected. In this case the circuit diagram shown in Figure 3 is modified by the short-circuiting of the contacts 107, so that all the clutch magnets 1 receive a resettin impulse. This method, however, requires that the time available for resetting is long enough for a wheel which has not been selected to move through a distance equal to the passage of a complete group of characters past the printing position. Thus, the operating cycle (Figure 2) is extended to include twenty-one or more divisions.

We claim:

1. A printing mechanism comprising a constant speed, continuously rotating drive shaft, a typewheel carrying sequentially arranged groups of type characters, said typewheel having a reset position associated with each said group of characters and normally being at rest in one of said reset positions, a normally disengaged clutch operatively connected between said drive shaft and said typewheel, means under control of a timed characterrepresenting electrical impulse occurring in a first half of a printing cycle for effecting engagement and disengagement of said clutch to bring said typewheel to rest with the character represented by said timed impulse at a printing position, one revolution of said drive shaft corresponding to half a printing cycle and to the passage of all the characters of a group past said printing position, means operative to engage the clutch at a predetermined time in the second half of the cycle and resetting control means driven in synchronism with the movement of the typewheel and operative each time the typewheel reaches one of said reset positions to eifect dis-engagement of the clutch to bring the typewheel to rest at the reset position following that from which the typewheel was driven.

2. A printing mechanism comprising a drive shaft rotating continuously at constant speed, a typewheel carrying sequentially arranged groups of type characters, the typewheel having a reset position associated with each group of characters and normally being at rest in one of the said reset positions, a normally disengaged clutch operatively connected between said drive shaft and said typewheel, means operative under control of a timed character representing electrical impulse occurring in a' first half of a printing cycle to engage the clutch to cause the drive shaft to drive the typewheel, one revolution of the drive shaft corresponding to half a printing cycle and to the passage of all the characters of a group past a printing position, means operative to dis-engage the clutch at a predetermined time during the first half of the printing cycle to bring the typewheel to rest with the character represented by said timed impulse at the printing position, means to effect printing from said character, means operative to engage the clutch at a predetermined time in the second half of the cycle and resetting control means driven in synchronism with the movement of the typewheel and operative each time the typewheel reaches one of said reset positions to effect dis-engagement of the clutch to bring the typewheel to rest at the reset position following that from which the typewheel was driven.

3. A printing mechanism comprising a drive shaft rotating continuously at constant speed, a typewheel carrying sequentially arranged groups of type characters, the typewheel having a reset position associated with each, group of characters and normally being at rest in one of the reset positions, a normally disengaged clutch operatively connected between said drive shaft and said typewheel, an elcctromagnet operable by a timed character repre- 8 senting electrical impulse to effect engagement of the clutch to couple the drive shaft to the typewheel to drive the typewheel from the reset position in which it is located, means operating in synchronism with the rotation of the drive shaft and effective to dis-engage the clutch to bring the typewheel to rest with the character corresponding to said timed impulse at a printing position, means to effect printing from said character, means operating in synchronism with the rotation of the drive shaft to energise the electromagnet to re-engage the clutch, a resetting cam driven in synchronism with the movement of the typewheel and means controlled by the cam effective to disengage the clutch each time a reset position of the typewheel reaches the printing position, whereby one of the groups of type passes the printing position for each energisation of the electromagnet by a character representing impulse.

4. A printing mechanism comprising a drive shaft rotating at a constant speed, a typewheel carrying sequentially arranged groups of type characters, the typewheel having a reset position with each group of characters and normally being at rest in a reset position, a normally disengaged clutch operatively connected between said drive shaft and said typewheel, an elcctromagnet operable by a timed character representing electrical impulse to engage said clutch to transmit drive from said shaft to said typewheel, a cam driven in synchronism with the drive shaft, a latch arm operated by the cam to disengage the clutch to bring the typewheel to rest with the character represented by said impulse at a printing position, means to effect printing from said character, means operating in synchronism with the rotation of the drive shaft to energise the electromagnetic to re-engage the clutch and a resetting cam driven in synchronism with the movement of the typewheel and effective to operate the latch arm to disengage the clutch each time a reset position of the typewheel reaches the printing position, whereby one of the groups of type pass the printing position for each engagement of the clutch by a character representing impulse.

5. A printing mechanism comprising a constant speed, continuously rotating drive shaft; a plurality of typewheels, each said typewheel carrying a plurality of groups of type characters arranged sequentially round the periphery of the wheel, each said typewheel having a reset position associated with each said group of characters and normally being at rest in one of said reset positions; for each said typewheel, a normally disengaged clutch operatively connected between said drive shaft and the typewheel, means operative under control of a timed character-representing electrical impulse occurring in a first half of a printing cycle to engage said clutch to cause said drive shaft to drive said typewheel, one revolution of said drive shaft corresponding to half a printing cycle and to the passage of all the characters of a group past a printing position, means operative to disengage said clutch at a predetermined time during the first half of said printing cycle to bring said typewheel to rest with the character represented by said timed impulse at said printing position, means for engaging the clutch at a predetermined time in the second half of the cycle, and resetting control means driven in synchronism with the movement of the typewheel and. operative each time said typewheel reaches one of said reset positions to effect disengagement of said clutch to bring said typewheel to rest at the reset position following that from which said typewheel was driven; and means for simultaneously eifecting printing from the typewheel characters brought to said printing positions subsequent to said predetermined time during the first half of the printing cycle and prior to said predetermined time during the second half of the printing cycle.

6. A printing mechanism as claimed in claim 2 comprising also means for identifying at least one predeter- -mined group of characters, the characters within the 10 predetermined group differing from those within the 8. Apparatus as claimed in claim 7 in which each remaining groups, the identifying means being adapted Wheel has means for releasing said locking device to to control movement of the typewheel after printing has print the character 0 when no selection has taken taken place to position the typewheel at the reset position place.

associated with the predetermined group. 5

7. Apparatus as claimed in claim 5 comprising also References Clted the file of thls a locking device for each said typewheel preventing a UNITED STATES PATENTS character from being printed from the wheel unless selec- 2,679,797 Keen June 1, 1954 has taken 2,692,551 Potter Oct. 26, 1954 

